Capacitors are widely used in integrated circuits. The capacitance of a capacitor is proportional to the capacitor area and the dielectric constant (k) of the insulation layer, and is inversely proportional to the thickness of the insulation layer. Therefore, to increase the capacitance, it is preferable to increase the area and k value and to reduce the thickness of the insulation layer.
A problem associated with the increased area is that a greater chip area is required. Conventional metal-insulator-metal (MIM) capacitors in integrated circuits have various horizontal comb structures. The horizontal structure capacitance correlates with inter-metal layer thickness. However, the thickness of an inter-metal layer is very difficult to control. This results in high variation of MIM capacitance in production for a target value. Accordingly, new methods and structures are desired for MIM capacitors.